ranta18

The chamber volume can be found with an inexpensive kit, but what abou the piston dome volume? Basically, you just need to know the cylinder bore, stroke, chamber volume, head gasket thickness, and piston to deck height to find the exact compression ratio. The only value I don't know is the piston dome volume.

Any ideas?

Here is a picture of them...

Natural Aspirations

Call Import Builders (Guessing on piston brand) and ask?

ranta18

I did. He said 10cc. But I just wanted to double check.

Bud's Machine

i use file fit rings gapped to near zero. install the piston on the crank with lots of heavy grease on the cylinder walls to seal the rings completely. lower the piston exactly an inch and measure cc's to top of bore (making sure the dome is below the top of the bore). drop the piston to exactly two inches from the top of the bore and measure again. double your first measurement and subtract from the total of the second measurement, this would be your dome volume.

ranta18

Plans are to wrap a thin strip of aluminum around the piston. Put the piston 2cm below the aluminum edge. Place the clear plastic cover w/ hole in it over the metal edge. Take a reading of the liquid in the graduated cylinder. Pour the liquid onto the piston until it fills up. Take another reading. pi*(bore/2)^2*2cm - the amount of liquid used should be the dome volume. I'm just trying to get a general idea of the compression ratio +/- .2

wacracing

Okay i place the piston in the cylinder block with the top rings insert and then turn the crankshaft to lower the piston an inch from the top of the cylinder bore .Then i grease the top of the block i place a peace of clear plastic plate with the hole in it and cover over the piston i use some green rubbing alcohol with a syringe to fill onto the piston until it fill take the reading that should be piston dome cc volume i'm just learning about piston dome volume

gstrudler

Combination of this. Install the piston in the cylinder, bring it to TDC then lower the compression height (not dome) of the piston one inch from the top of the block (or something easy metric) using a dial indicator. Cap it off and measure the volume. Now calculate the theoretical volume of the cylinder area you just measured (3.14 x (0.5 cylinder diameter)^2 x height [one inch in this case]). Make sure you convert so you are using the same units. Subtract your measured volume from the theoretical volume and this should be your dome volume. This can also be used for dished pistons, you will just end up with a negative number.